1. Field of the Invention
The present invention relates generally to hand-held tools and, in particular, to hand-held pruning tools.
2. Description of Related Art
Hand-held tools known as pruning tools are used to cut the branches, stems, and stalks of plants to control their growth, enhance their appearance, and harvest their products. Pruning tools typically have a scissors-like cutting head attached to one or two handles. A lopping shear, sometimes called a lopper, is an example of a pruning tool with two relatively large handles. A pole pruner is an example of a pruning tool with only one handle.
The cutting head is usually metal. The handles are made of various materials, including fiberglass, metal, wood, etc. The handles may be solid. However, hollow handles are often preferred because of reduced weight.
A hollow handle must, of course, be securely attached to the cutting head in some manner. A common problem is providing a solid, durable connection between the cutting head and the hollow handle. This is especially true where the pruning tool is used to sever large branches and undergoes excessive strain or where the pruning tool is continually used in a commercial environment, such as, for example, harvesting grapes.
FIG. 1 illustrates one prior art approach to attaching a hollow handle 200 to a leg 212 of a cutting head 210. As shown, this prior art system employs a hard rubber ferrule 220 having a central body portion 222 and an external skirt 224 which defines a tubular space 226 for receiving an end of the hollow handle 200. When so received, the central body portion 222 fits tightly inside of the hollow handle 200 and the external skirt 224 fits tightly around the hollow handle 200. A central aperture 223 is defined in the central body portion 222 to receive the leg 212 of the cutting head 210. An interconnection between the hollow handle 200 and the cutting head 210 is made secure with a pair of pins 230 inserted through a pair of aligned apertures respectively formed through the ferrule 220, the hollow handle 200, and the leg 212 of the cutting head 210.
FIG. 2 illustrates another prior art approach involving a hollow handle 300 and a ferrule 320 of a different construction. Here, the cutting head 310 has a leg 312 with a width "W" that is slightly larger than the inside diameter of the hollow handle 300. The ferrule 320 has an upper cap portion 321 and an elongated body portion 322. A rectangular aperture 323, conforming to the cross-sectional shape of the cutting head leg 312, extends though the ferrule's cap portion 321 and elongated body portion 322. Four elongated ribs 324 are provided along the exterior of the elongated body portion 322 to provide an X-shaped cross-section. The four elongated ribs 324 are dimensioned so that they fit snugly within the interior of the hollow handle 300. An upper portion 325 of two opposing ribs 324 are open so that an edge of the leg 312 can make direct, metal-to-metal contact with the interior of the hollow handle 300. The metal-to-metal contact between the leg 312 and the hollow handle 300 in one dimension, in conjunction with the close fit between the ferrule 320 and the hollow handle 300 in two dimensions, provides an overall tight fit.
The tool head to handle connections of FIGS. 1 and 2 work relatively well for their designed purpose. However, to ensure a solid assembly, they both require tight control over component size variation during manufacture. If production results in size variation, the result may be an overly tight "line to line" fit or an overly sloppy fit. This is especially true if the cutting head, or components, are made of cast metal that have a relatively wide production range in terms of dimension. In addition, the hollow handles are likely to be purchased from outside sources. Consequently, dimensional variation of the handle may not be under the direct control of the pruning tool manufacturer.
Moreover, a connection according to either FIG. 1 or FIG. 2 is not readily renewable in the field. This is particularly problematic where the tool is being used in a commercial environment, where down time is money lost. The prior art tools do not generally provide for quick and easy replacement of the handle or tool head if accidentally damaged.